storm_relative_helicity

metpy.calc.storm_relative_helicity(u, v, heights, depth, bottom=<Quantity(0, 'meter')>, storm_u=<Quantity(0.0, 'meter / second')>, storm_v=<Quantity(0.0, 'meter / second')>)[source]

Calculate storm relative helicity.

Calculates storm relatively helicity following [Markowski2010] 230-231.

\[\int\limits_0^d (\bar v - c) \cdot \bar\omega_{h} \,dz\]

This is applied to the data from a hodograph with the following summation:

\[\sum_{n = 1}^{N-1} [(u_{n+1} - c_{x})(v_{n} - c_{y}) - (u_{n} - c_{x})(v_{n+1} - c_{y})]\]
Parameters

  • u (array-like) – u component winds

  • v (array-like) – v component winds

  • heights (array-like) – atmospheric heights, will be converted to AGL

  • depth (number) – depth of the layer

  • bottom (number) – height of layer bottom AGL (default is surface)

  • storm_u (number) – u component of storm motion (default is 0 m/s)

  • storm_v (number) – v component of storm motion (default is 0 m/s)

Returns

  • pint.Quantity – positive storm-relative helicity

  • pint.Quantity – negative storm-relative helicity

  • pint.Quantity – total storm-relative helicity